Self-seating furnace cover



March 25, 1958 P. c. OSTERMAN ET AL 2,827,864

SELF-SEATING FURNACE COVER Filed June 1, 1955 INVENTORS PHILIPC.OSTERMAN ROBERT L. HATFIELD FIG.4.

ATTORNEY United Stats SELF-SEATING FURNACE COVER Application-Jamel,1955, SerialNo. 512, 553

9 Claims. (Cl. 110-177) This invention relates in general toimprovements in metallurgical heat treating furnaces and is concernedmoreespecially with improvements in the covers and' cover-suspension andcover-operating means of furnaces of the vertical type.

Types of treating furnaces to which the invention is particularlyadapted are normally cylindrical steel shells, but may be square orrectangular depending upon their particular. function, and linedywithfire brick or other heat insulating refractory. The heating chamberextends, generally vertically and is fired by burners strategicallyspaced about the periphery of the chamber. In some instances the burnersare positioned tangentially so. as to give a swirl to the heatedatmosphere.

Through the open top of such a furnace the Workpieces, individually orstacked, or in baskets, are lowered by means of a crane or air-hoistapparatus and the rela- .tively heavy cover replaced. If the Work is tobe given a special gaseous treatment, such as carburizing, it is .placedwithin a retort and the whole assembly lowered into the heating chamberof the furnace. Thepipe connections that supply the retort with thegaseous atmosphere during the heating process must of necessity extendthrough the cover of the furnace.

The covers of the upright styles of furnaces are not only large indiameter, assumingthe furnace is round, but very heavy and difficult tomanipulate. Theytoo are made. of firebn'ck or suitable refractorymaterial and usually banded with iron to hold the individual brick.components of the cover together. A cover several inches thick andmeasuring 2 or more feet across is not uncommon .and presents a.difficult problem to move on and off the furnace to permitwork change,especially when the furnace is hot.

Prior .to this inventionthe cover was slid-laterally over the-furnacetop. to an improvised shelf, and, in some instances the cover waspivoted so as to be slid over the ,top of the furnace and to one, sidethereof. Such cover operating methods inaddition to necessitating a workarea substantially twice the floor space of the furnace, werecumbersome, and excessively hard on the refractory materials ofboth-cover and furnace. Moreover, the

atentO abrasion and abuse the covers received soon rendered themillfitting and no'longer tight so that they soon needed replacement.

The present invention aims to render available an improved cover andcover-suspension means that eliminates I problems of abrasion, wear, andabuse, and by which the unifofm'ly and acquire a uniform treatmentthroughout.

Afurther aim of the invention is the economical =conr 2,827,864 PatentedMar. 25, 1958 struction ofa ruggedand serviceable cover assembly theoperation-of whichprevents abuse and eliminates wear on the refractorymembers to the end of prolonging the useful life of the parts.. Theinvention also aims to provide ajcover construction and supporting meanstherefor that maybeconstructedof relatively fewparts and which isconveniently and expeditiously operable to permit accessto the heatingchamber of furnace, which avoids theneed to disconnect retortconnections, temperature controls and suchother externally connecteddevices that may be used within the furnace during a treating process,whenever the 'furnaceis opened or closed, and a cover suspension whichis adjustable to fitthe top of the furnaceand thereafter automaticallycompensating and selfadjusting to minor irregularities in the refractoryunits so that when closed and in operating position the furnace chamberis elfectivelysealed against escape of fumes and the lossof heat.

In achieving the objectives of the. invention his proposed toconstruct afurnace cover in two sections and suspend or support each at-itsapproximate. gravimetric center. from an ,overarm .ina manner such as toprovide a limited floating movement about transverse axes- Each armaextends rearwardly across the top of the cover and the rear end thereoffunctions as a pivot point about :which the associated cover section islaterally movable.

The .overarm pivots are, in accordancewith the:ob.jec tive of avoidingwear on the refractories incident toslid- .ing brick-on-brick, .alsoconstructed for pivotal movement about. a horizontal axis whereby itbecomes possible to effect alifting .of the cover and aseparationthereof from the furnace proper before the-cover sections are swunglaterally. By constructing the cover in two sections-and by providing anopen-sided recess in one orboth sections along their "mating edges forthe passage-of retortfittings, piping, etc., such connections need notbe disturbed each time the cover is openedor closed. The tilting.of:each cover-section axisrmay be effected manually; however,- it ispreferred to construct the parts for power actuation .as-by an air-cylinder, valve controlled, so as to :relieve the attendant :of thetask ofliftingra heavy masswhile at the same time moving the masslaterally.

Other-objects and advantages will-be inpa-rt indicated in the followingdescription and in part rendered apparent therefromin connection withthe annexed drawlngs.

To enable others skilled in thewart sofully to apprehend the underlyingfeatures hereof that they may :embody the same in the various wayscontemplated bythis invention, drawings depicting a preferredtypical-con struction .have beenannexed as parts "of this disclosureand, in such drawingsg like characters of -referencedenote'correspondingparts throughout all thewiews, of which:

Fig. 1 ofthe drawings 'is' an elevation of a vertical vtfurnaceembodying cover-constrnction and cover-suspension features of thisinvention.

Fig. 2 'is :a plan'viewzof the furnace of Pig. 1 illustrating theclosedposition of the cover sections in :full'lines and the openpositionthereof in dotted lines.

Fig. 3 isv a front view of the cover supporting means.

Fig; 4 is a rear view of the furnace illustrating :a preferred means forlifting both cover sections simultanea ously.

Referring more particularly to Fig. l of the drawings the furnaceillustrated comprises essentially a body portion 10 in which aheatingchamber 11 is provided. The chamber 11 may be heated in' any suitablemanner such as :by oil or gas lbur-ners indicated at 12. The "furnace islined about its sides and bottom with a heat insulating refractory '13.Workpieces to be heated or otherwise treated are lowered into:thetchamber 11 .from' thevtop'aud the opening closed by a refractorycover 14. Furnaces of this type are usually vented at the bottom byconventional means.

In accordance with the present invention, it is preferred to constructthe cover 14 in two sections-A and B which when in abutting relation asshown in full lines in Fig. 2 completely cover the open end oftheheating chamber with a generous overlap about the edges thereof. Eachcover section is made of insulating refractory brick, preferably bandedwith iron or steel, andis overlaid with a pair of spaced angle irons 15and 16. The pairs of angle irons extend preferably lengthwise and aresuitably secured to their respective cover sections along lines thatpass through the approximate center of their masses, and one angle iron16 of each pair is made to extend well beyond the cover to function as ahandle. 1

The space between the vertical walls of the angle irons of each pair ofcover irons is adapted loosely to receive a relatively flat overarm 17(18) that extends generally horizontally from a vertically adjustablepivot shaft 19 (20). Each shaft is journaled in an upper bearing 21 anda lower bearing 22, the latter having an adjustable vertical-thrustpivot in the form of an adjusting screw 23 and a jam nut 24. Byadjusting the thrust pivot 23 in or out with relation to the lowerbearing bracket 22, the pivot shaft 19 (or 20) may be adjusted up ordown and correspondingly adjust the cover-carrying overarm 17 (18) up ordown. Height-adjusting meansof this character enables one properly tofit the cover to the furnace, inasmuch as there is always the likelihoodof variations in refractory thickness on assembling the furnace or coversections.

Each of the overarms 17 and 18 is connected with its associated coversection in a manner as to permit a limited floating action of the cover.In the arrangement illustrated, the floating action is obtained byutilizing two pivot pins 25 and 26 which pass through the upstandingflanges of the angle irons and through the overarm 17 (18) that isloosely guided and confined in the space between. Preferably the outerhole 27 in each overarm bar is elongated so that the cover section maytip from front-to-back slightly about the rear pivot pin 25. Each coversection is also free to tip from side-to-side slightly by virtue of thelimited clearance provided between the upstanding sides of the coverirons 15 and 16 and the overarms 17, (18) confined therebetween.

The journal bearings 21 and 22 of the pivotal shafts 19 and 20 aremounted upon a tilting frame 30 that in turn is mounted for oscillatorymovement about an axis 31 located at the upper end of the frame. Theaxis 31 comprises a shaft member mounted in straps 32 secured to thefurnace exterior near its top. The straps 32 extend along the outersides of the tilting frame 30 and function as guide means therefor. Apair of similar straps 33 are located near the lower end of the furnaceand extend along the outsides of the lower portions of the tilting frameand serve to guide the lower end thereof.

It will be seen from the foregoing that each cover section is suspendedfrom an overarm at its approximate gravimetric center and has a limiteduniversal movement relative to its support that enables it to beautomatically self-seating and self-adjusting to any minor irregularityin the refractory of the furnace top. It will also be seen that atilting of the carrier frame 30 from the position shown in full lines inFig. 1, to the dotted line position, correspondingly rocks the pivotshafts 19 and 20 and their respective integral overarms 17 and 18counterclockwise about the horizontal pivotal axis 31 and effects alifting of the cover sections A and B bodily off the furnace top. Whenthe cover has been lifted and physically separated from the top of thefurnace proper, the cover extensions 16 may be grasped by the attendantand one or both cover sections swung laterally about the axes of thevertical pivot shafts 19 and 20 to positions indicated in dotted linesin Fig. 2. The furnace opening is closed 4 by manipulating the parts inthe reverse order, i. e., the cover extensions 16 are first moved toclosed position which places the cover sections A and B directly overthe furnace opening, and then the carrier frame .36 is tilted to itsfull line position (Fig. 1) which lowers the self-seating cover sectionson to the top of the furnace and in this way dragging or sliding thecover on the top of the furnace is effectively eliminated. It will beseen further that when the furnace is closed as in Fig. 1, the pivotshafts 19 and 2t? slant away from the furnace at their lower ends andmakegreater than a right angle with the generally horizontal plane ofthe cover sections 14. When in such a position the weight of the coversections tend to hold the sections in substantially closed position overthe furnace opening. It will also be seen that by tipping or slantingeach pivot shaft .20 inwardly toward each other at their lower ends asindicated in Figs. 2 and 4, a tilting of the frame 39 to cover-raisingposition causes the cover sections to tend to swing laterally in thedirection of lean of the pivot shafts, to

tilted outwardly at their lower ends so that the covers tend to leantoward one another on being raised oif the furnace top and naturallytend to move toward furnaceclosed position. We prefer,-however, to mountthe pivot shafts so that the covers tend to stay open and so that theyare out ofthe way during work-change operations. To aid the attendant incentralizing the cover sections a fixed stop 35 may be secured to thefurnace against which the cover arms 16 may abut when the furnace isclosed or nearly closed. V Tilting of the above-carrier frame 30 may beeffected in a suitable way as by manually-operated linkages or bypower-operated means. In the form shown herein a power cylinder 40 isprovided whose piston rod 41 connects with a link 42 that also pivotallyconnects with the carrier frame 39 as at 43. A reversing valve indicatedat 44 may be provided at a convenient location for controlling thedirection and extent of action of the power cylinder. With such anarrangement very little effort is now required on the part of theattendant to open or close the furnace and hence the operation may beperformed quickly and with consequential savings in furnace heat andwith marked improvement in the uniformity in quality of the heattreatment given to large pieces or to small pieces processed in bulk.

When work is to be treated in a gaseous atmosphere, the retort islowered into the furnace and connections made to an external sourceof-treating gas. By utilizing a sectionized cover of this invention, anopening H may be provided in one or both mating sides of the coversections adapted to surround the retort piping or connections andwhereby the latter need not be disconnected each time the furnace isopened. This feature enables one not only to save considerable time incharging and recharging the furnace but such operations requiring acooling of the work in the same atmosphere may be carried on merely byswinging open the cover and elevating the retort and its chargeof workas complete assembly and standing it aside to cool. Jointed or fiex=ible connections may be provided in the gas lines for this purpose, aswill be understood, but they need not be disconnected or the gas turnedoff when the assembly is elevated out of the furnace.

Without further analysis, the foregoing will so fully reveal the gist ofthis invention that others can, by applying current knowledge, readilyadapt it for various uti: lizations by retaining one or more of thefeatures that, from the standpoint of theprior art, fairly constitute 5.essential characteristics of either the generic or specific aspects ofthis invention and, therefore, such adaptations should be, and areintended to be, comprehended within the meaning and range of equivalencyof the following claims.

Having thus revealed this invention, we claim as new and desire tosecure the following combinations and elements, or equivalents thereof,by Letters Patent of the United States:

1. In a furnace of the character described having generally verticallydisposed side walls defining a heating chamber adapted to receive workto be heat treated and forming a work-receiving opening in the topthereof, the combination of movable closure means for the workreceivingopening comprising a pair of complementary cover sections normallypositioned in abutting relation when in closed position over thework-receiving opening, means for supporting each cover sectioncantileverfashion in relation to the work-receiving opening comprising ashaft member journaled in relatively fixed bearings for movement about agenerally vertical axis and an overarm integral with each shaft member,means mounting a cover section to each overarm, a frame structuremounted to said side walls for pivotal movement about an axis transverseto the axis of said shaft members for supporting the bearings for theshaft members, fluid means including a piston and cylinder operativelyconnected with the frame structure for tilting said frame structureabout its pivotal axis whereby to effect arcuate movement of said shaftmembers and a corresponding arcuate movement of the cover sectionsrelative to the top of the said side walls, and means thereafteroperable to swing one or both cover sections laterally about the axis ofits related shaft member to permit access to the heating chamber of thefurnace.

2. The combination of claim 1 in which each cover section is pivotallyconnected to its overarm whereby each cover section is renderedindependently movable and thereby automatically self-adjusting to thefurnace,

and in which each of said cover-carrying shaft members are axiallyadjustable in said journal bearings to compensate for variations andirregularities in the mating faces of the cover sections and furnacetop. w

3. In a materials heat-treating furnace having side walls defining aheating chamber and forming a work-receiving opening in the top thereofthe combination of, a cover assembly adapted to close the work-receivingopening leading to the heating chamber of the furnace comprising arefractory cover member, means supporting said cover membercantilever-fashion over the work-receiving opening in the furnaceincluding a shaft member mounted for pivotal movement about asubstantially vertical axis, journal bearings for said shaft member,frame means mounting said journal bearings in axial alignment, meansmounting said frame means for movement about a generally horizontalaxis, and means for tilting said frame means about its said horizontalaxis to effect a tilting of said cover-carrying shaft member and alifting of the cover member generally vertically off the furnace wallswhereby to permit the cover to swing laterally in the direction of leanof the axis of said shaft member to furnace-open position.

4. In a materials heat-treating furnace having a heating chamber andside walls defining said chamber and forming a work-receiving openingleading to said chamber the combination of a cover assembly adaptednormally to rest on the side walls and to close said workreceivingopening comprising a refractory cover member, means supporting saidcover member in cooperative rela tion with said opening andcantilever-fashion to the said side walls including a substantiallyvertical shaft member mounted for pivotal movement about itslongitudinal axis, bearing means for said shaft, frame means mounted formovement about a generally horizontal axis for mounting said bearingmeans, means mounting said frame means to the said side walls fortilting movement about said generally horizontal axis so that when saidframe means is tilted about its axis said shaft member is tilted andsaid cover member lifted off the side walls and rendared free to movelaterally about the pivotal axis of said supporting shaft away from thework-receiving opening.

5. In a materials heat-treating furnace having a vertically disposedheating chamber and side walls defining said chamber and forming awork-receiving opening at the top of said chamber the combination of acover assembly adapted normally to rest atop the side walls and to closesaid work-receiving opening comprising a pair of movable cover sections,means supporting each cover section in cooperative relation with saidopening and cantilevenfashion to the said side walls including a shaftmember for each section mounted for pivotal movement about asubstantially vertical axis, bearing means for each of said shaftmembers, frame means mounting said bearing means, means mounting saidframe means to the said side walls for tilting movement about agenerally horizontal axis so that when said frame means is tilted aboutits axis said shafts are tilted and said cover sections are lifted 01fthe side walls and are rendered free to move laterally away from thework-receiving opening about the pivotal axes of their respectivesupporting shaft members, and means for tilting said frame means.

6. The combination of claim 5 in which the means for supporting eachcover section includes an arm member operatively connected with eachshaft member and in which each cover section is pivotally connected toone of the arm members at the approximate center of mass of the coversection so that each cover section may move independently and relativeto its arm member and thereby rendered self-adjusting to the furnaceside walls.

7. The combination of claim 5 in which each of said cover-carrying shaftmembers is mounted in said frame means for axial adjustment relativethereto.

8. The combination of claim 5 in which at least one of said coversections has an opening in its edge adjacent the other cover sectionthrough which a portion of the workpiece being treated may extend whenthe cover sections are in closed position.

9. In a materials heat-treating furnace having a vertical heatingchamber and side walls defining said chamber and forming awork-receiving opening at the top of said chamber the combination of, acover assembly adapted normally to rest on the top of the said sidewalls and to close said work-receiving opening comprising a pair ofcomplementary cover members, means supporting each cover member incooperative relation with said opening and cantilever-fashion includinga shaft member for each cover member mounted for pivotal movement abouta variably inclined axis and an overarm integral with each shaft member,operative connections between each cover member and one of saidoverarms, bearing means for each of said shaft members, frame meansmounting said bearing means, means mounting said frame means to the saidside walls for tilting movement about a generally horizontal axis sothat when said frame means is itlted about said generally horizontalaxis said shaft members are tilted to vertical positions and said covermembers lifted off the side walls and rendered free to move laterallyabout the pivotal axis of said supporting shaft away from thework-receiving opening.

References Cited in the file of this patent UNITED STATES PATENTS873,573 Markmann Dec. 10, 1907 1,073,912 Koch Sept. 23, 1913 1,930,323South et a1; Sept. 16, 1930 2,097,932 McKee Nov. 2. 1937

